启动systemctl start docker
报错信息：
System has not been booted with systemd as init system (PID 1). Can't operate.
Failed to connect to bus: Host is down
解决方式
sudo apt-get update && sudo apt-get install -yqq daemonize dbus-user-session fontconfig
sudo daemonize /usr/bin/unshare --fork --pid --mount-proc /lib/systemd/systemd --system-unit=basic.target
